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14.5" Southbend Lathe


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I have a 14.5" Southbend lathe with the motor under the head stock. It has a flat belt running from the head stock pulleys to the jack shaft pulleys. It is a 1hp single phase machine. Whenever I take a heavy cut the belt starts squeaking and then slips off. the book says it should be able to take a larger cut than I can get before the belt slips off. I never get to the point where the motor starts slowing down. I also wonder could this lathe safely be fitted with more than a 1 hp motor it seems like by the way its built it could handle a lot more. I have not been able to find any info on this topic.
Thanks
Tim

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I have a 14.5" Southbend lathe with the motor under the head stock. It has a flat belt running from the head stock pulleys to the jack shaft pulleys. It is a 1hp single phase machine. Whenever I take a heavy cut the belt starts squeaking and then slips off. the book says it should be able to take a larger cut than I can get before the belt slips off. I never get to the point where the motor starts slowing down. I also wonder could this lathe safely be fitted with more than a 1 hp motor it seems like by the way its built it could handle a lot more. I have not been able to find any info on this topic.
Thanks
Tim


Having dealt with flat belt equipment up here in the older boat yards I would look at alignment first.If the alignment is right and the mounts are sound with minimal slop in any of the pivot points or bearings then a flat belt will remain on the pulleys and just slip till it burns if you let it.What looks like proper alignment can be thrown off under load if there`s any appreciable wear to things like motor mounts or other pivot points.This sounds like what may be happening with your machine.
I am assuming that all the pulleys are crowned metal factory items that run true and none are home made wood with any problems and none of the shafts are bent or worn beyond acceptable tolerances.
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Does this happen in all the speeds (other belt positions)? How about the belt itself? Newer belts known as power transmision belts with a rubber face can transmit more power than leather belts. Did the direction of the belt somehow get reversed? Also, are you oiling the headstock bearings every time you use it?

One horse power should be O.K. I have a 16" Southbend with a 2 hp motor, single phase.

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Does this happen in all the speeds (other belt positions)? How about the belt itself? Newer belts known as power transmision belts with a rubber face can transmit more power than leather belts. Did the direction of the belt somehow get reversed? Also, are you oiling the headstock bearings every time you use it?

One horse power should be O.K. I have a 16" Southbend with a 2 hp motor, single phase.

I have not run it in all of the speeds the lathe is capable of but it seems to happen in the most speeds. Both high and low back gears in or out.
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Just as a sanity check I`d run a straight edge across the edges of the pulleys and check the alignment between them.

Can you post pics of the drive train to include the linkage and motor mount?That would help a lot.

Don`t know how old this machine is but if it`s old enough to have a leather belt one of the diagnostic tricks one of the old timers showed me was to pull the pin out of the splice and reverse the belt.If the belt threw to the other side then the belt was at fault,if it threw to the same side then he checked the alignment of the pulleys, if that was good then he would have one of us watch while he ran the machine under load to see what was shifting and then he``d fix that by whatever means.
That`s the progression I learned on line driven machinery,hope some of it`s a help to you.

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I have a 14.5" Southbend lathe with the motor under the head stock. It has a flat belt running from the head stock pulleys to the jack shaft pulleys. It is a 1hp single phase machine. Whenever I take a heavy cut the belt starts squeaking and then slips off. the book says it should be able to take a larger cut than I can get before the belt slips off. I never get to the point where the motor starts slowing down. I also wonder could this lathe safely be fitted with more than a 1 hp motor it seems like by the way its built it could handle a lot more. I have not been able to find any info on this topic.
Thanks
Tim


Tim,
I've seen all the things mentioned in the previous posts be the problem but it also may just be that the belt has streached or worn just a bit and is too loose.
You'll be surprised how tight a flat belt can and has to be to work properly. If I were you I might try shortening the belt by 1/2" to 3/4" and see if that doesn"t improve things.
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  • 11 months later...

Never overlook the obvious.

If the belt is misbehaving, ... it might just be the belt.

"Laced" belts are often "out of square", ( making them "tighter" on one edge ) ... and will have a tendency "walk" toward the tighter edge.

Try turning it around, and see if it "walks" in the other direction.

The automotive "serpentine" belts are popular as replacements for the 1" wide flat belts, found on many smaller lathes, ... but I suspect that your machine uses a wider belt.

Industrial "timing" belts come in a variety of widths, .. and work very nicely on crowned sheaves.



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